Bituminous product and method of making



Patented Dec. 15, 1942 BITUMINOUS PRODUCT AND METHOD OF Q MAKING Benjamin Albert Anderton, Clii fside Park, N. J., assignor, by mesne assignments, to Allied Chemical & Dye Corporation, a corporation of New York No Drawing. Application July 16, 1938,

Serial No. 219,645

6 Claims. ,(Cl. 106-278) This invention relates to tar products of a novel type adapted for use as roofing pitches upon steep roofs.

Coal-tar pitch has outstanding waterproofing qualities, is immune to climatic variations, is selfhealing and is technically toxic to fermentation or decay.

The use of coal-tar pitch, however, has been limited to relatively flat decks, i. e. dead level to inclines of less than two or three inches to the foot. This was due to therelative susceptibility of coal-tar pitches to temperature change. Thus, for steep work, and where a form of builtup roofing was desired, it has been expedient to resort to the use of so-called high melting point asphalts, or bitumens containing inert fillers.

Originally, built-up roofs were designed for relatively flat decks. Later, as structural trends and necessity gave impetus to industrial steeproofed construction, the economy of built-up roofs suggested their use in this field.

In the early days saturated burlap or felts were fabricated into a membrane and were given a finishing coating of tar or tar paint sprinkled with sand for use on steep roofs, Then came the pitch and tar job mixtures, to which, later, were added nous material. When oxidation, cracking and disintegration have progressed to the stage permitting water to reach the underlying fabric, disintegration of the fabric. sets in. and the usefulness of the roof is practically at an end.

The more completely the bituminous material, or membrane, is protected by slag, gravel, tile, etc., the slower the rate of change in the material. Where the bitumen is unprotected, obviously the rate of change is rapid and the life of the roof materially curtailed. Non-techniinert fillers, lime, etc. These mixtures might be 1 termed experiments which, with the advent of cracking and blowing processes in the petroleum industry, gave way to petroleum residual asphalts. These asphalts were plentiful and rela tively inexpensive, and because of their relative non-susceptibility to slide, required no job mixing or filler. 7 Frequently, however, such asphalts are not uniform, and because of their relatively high softening point range are difficult to heat,

are relatively highly viscous when molten and consequently hard to spread. Thus, premium asphalts were developed to inherently lower melting points or "cut back with oils to facilitate heating and spreading; inert fillers were commonly added to promote stability on the roof. The addition of these fillers, however, does not improve the relatively deficient waterproofing characteristic of the bitumen and reduces the develop weaknesses which result in unsightly cheesiness or serious leaks. These weaknesses are acelerated where no wearing surface is provided. The period of serviceability depends upon (1) the amount of protection given to a bituminous material, and (2) the quality of the bitumi- 1 cally, asphalts in generalfall short of giving ideal protection against .water and climatic change for extended periods of timeoomparable with the life of other building elements.

It is an object of the present invention ,to provide new tar products which are relatively free of the disadvantages of ordinary tar products or asphalt products.

A further object is to provide products having properties'which render them easy to apply, resistant to weathering, free from tendencies to bleed at the highest temperatures and from brittleness at the lowest temperatures of normal use, water repellent, and unaffected by fermentation or decay. g

Further objects will appear from the following description of my invention.

It is known that the character, of coal-tar pitch may be modified by heating the pitch with coal, such as bituminous coal, cannel coal, lignite, and the like. Such products are shown, for example, in Austrian Patent 90,380, British Patent 316,897, and United States Reissue Patent 17,762. The products of the present invention differ from such prior products in that theypossess a combination of properties adapting them for application as roofing pitches to steep roofs.

While tar products have been applied to roofs with a slope perhaps as steep as three inches per horizontal foot, they could not be employed satisfactorily upon steeper roofs. The products of the present invention, on the other hand, are

pitches. Moreover, they retain all the desirable properties of ordinary coal-tar pitch, such as water repellency,'oxidation resistance, and toxicity towards microorganisms of decay. In addition, they have pronounced non-sliding characteriisticsl, at; the vhighest temperatures of servl? ice and are less brittle and liable to crack at the lowest temperatures of service. In these respects, they are equal to or superior to roofing asphalts.

The products of the present inventionmaybe obtained by heating a mixture of tar oil and pitch constituents with coal under certain specific conditions of control to be delineated.

The mixture of tar J and pitch constituej ts normally should have a specific gravity between 1.1 and 1.22 at 38 0., compared with water at' 15.5 C., and preferably between 1.10 and 1.20. a

It should have an "Engler" specific viscosity not less than 2.0 at 80 C. It should contain not morethan %"of-oils distil1ingoff below 235 0. andnotmore 'than 25% of oils distilling ofi below 300"- CJ, when tested according toA. S. T. M.-

Standard MethodD-30. The residue -'ofdis-v tillatio'n to 30Q ..:'C. -sho uld have afloat test not above 1'30-s'econds and'normally not'abov'e 80 sec- The" tar'-oil-pitch-constituent mixture above deflnedisnot arr-ordinary coal tar or coal-tar pitch I and is distinguished from such products by its high content ofhi'gh-boiling oils which results i Wing. coal-tar oil having the following c'hara'ctere in the low float test of distillation'residue previously indicated Coal-tar pitches of equally low 1ow'-bolling distillate content ordinarilyflhave a 'distilla'tion' resi'due float test of 150 to 300 seconds --at--70- C.- Itis distinguished from ordinary tar oils on the-other hand -by' its content' of pitch 1 "constituents, reflected in its high viscosity. The products of my invention 'may'best be 1 a mad'e by employing'a good grade of bituminous coal. Anthracite hasnot been found 'suitable.

- Sub-bituminouscoals, lignite and brown coal, for

" example; are dispersabie only with difllculty." My

" experienc-has-indicated that, to avoid gel-like products hereinafter discussed, higher digestion temperatures are required for these'coalsand.

since dispersion is less complete} correspondingly more coal should be used, and undispersed'residue it separated. Several cannel coalshave been emplayed with some success. 7 The percentage of coal "digested in the digestion medium may be between 7% and and preferably between 15% and are the mostsatisfactory; since with all of such coals that I have employed homogeneous 'products having the desired properties are readily obtained. Among the bituminous coals, I have found that those having pronounced coking properties are very suitable for digestion. Goals of low volatile content are especially desirable, since their dig'estion is more easily controlled, and superior products are obtained. Among the coals which I have found satisfactoryfor preparation hereinafter more fully of products of my invention arelower Freeport Seam steam coal, Pennsylvania low-volatile bituminous coal, Ohio non-coking'coal, low-volatile West Virginia coking coal, and German bituminous coals (Steinkohlen).

The heating process forlproducing the products of the present invention must be carefully ,con-

trolled. For the digestion of anyone coal to pro:

duce a maximum dispersion of coal constituents l0 ,a certain minimum temperature of heating is required. This temperature produces gel-like products which are relatively unstable at. high ties'for application to the roof. Furthermore, 15 such" gel products are difficult to control in production. The minimum temperature referred to is inadequate to produce the products of 'myinvention and I have found that a temperature between 20- and 100 higher and preferably be- 20 tween and 70 higher should be employed.

A: suitable'test to establish the digestion temperature required for making-the products-of the present invention involves heating the coal'under digested at a temperature 'lower than suitable for 3 the purposes of my invention. -I n"m'aking such a '.;:tures-shouldbe selected sufficiently close s that I the temperature of' maximum consistency or 7 maximum softening point will be reasonably close temperatures and of unsuitable physical proper consideration with a suitable digestion medium. I

. for afixedperiod of'time at a series; of digestion fztemperatures andd'etermining the consistency of the products thus obtained. The 'producthav ing the. maximum softening point will have been series a of determinations, consecutive tempera- 35 to'one'of the temperaturesac'tually selected. The

satisfactory.

Te 75 parts 0;. this on 25 that, weight of the puiverized .coalto beetested areaddedr' The mix-.

.ture is heated with agitation'for fivehours at a v 5 5 temperature, previously-.rselected; f for example 245 (3., and the-softening point of the product is heated at a higher te'mperatureiisay270 0., for a similar period, andjthlrd and fourth-samples .may be. heated at 295? and 320C. for a similar 69 period, the softening- -points ofthe products in each case being determined at hourly intervals after the selected te'mp'eratureis reached;

- determined every hour; Another sample is then mFrom a series of such determinations it win be tion temperature and tlme until it reaches amaxas the'temperaturerises.more and more coal becomes dispersed until finally all-of the constitu-j.

70 nts capable of disper io are temperature rises further, decomposition of th dispersedconstltuents takes'place, as evidenced by evolution of fixed'gases and volatile liqueflable hydrocarbons containing paraflinic bodies, the 7 formation of acidic constituents, and'a change in imum. This may "be explained on the'b'asis that.

' found that the softening point-riseswith-digesthe proximate analysis of the digested coal, evi- C., and 46.l C. and are distilled by method danced; lay-"e: reduction in volatile combustible D20-30oi the American Society for TestingMatematten The softeningpoints' of'the products obrials, andthe softening points of. the distillation taine'd at higherdigestion:temperatures-fall below residuesaredetermined. Iir-aproduct-during this the maximum. 1' The type of oil described is a par-. 5 distillation tends to-40am excessively, the digesticulaily suitable digestion-medium for "the pur-- Wtion temperature employed; was below the optipose since its use permits 'ready'discernrnent of 1* muin temperature; Thistest serves as a clarifi- "the maximumconsiste'ncyz The'larg'e percentage cation; of the softening. point tests of the first -of coal selected also iavorsobservation of the series of runs .40! courserthe product should be changes in properties produced'by' changes in the lll'homogeneous. When reheated to; liquefaction coal. .l a. .t xtemperatufe it'should llquefy without prolonged 2' =The'preferred products of the present invention: heating. f- I Y 1 s v :exhibit'the-following characteristics: 2 Aeomparison between-the softening point of m i OafiQQ -I i the productcand that of the residue remaining I is. after the-distillation test may be used to estabv. o v r a -lish the stability of:-thei.product towards heat. pgnfitriatmv at f 'P Thus, if the softening point of thedistillatidn Penetration at 46.1 C. not more than 120 g I i i z .residue is lower than that of theproduct before Per cent soluble in carbon disulfide. at least specific gravity C N50 6 least 1 20 v distillation, or isnot higher in proportion to the 7 f ,1 v: 1' aotpercentage ofdistillate,aspcomparedtoichanges 1 For commercial operations and particularly for in softening .point; shown --by:-.heat -stable pitches a fa f pro ctsof the. pr ferred type 1tunder-similar distillation conditions; the product is desirable thattheyop imum tempera ur for is undesirably lacking instability and aa-higher Penetration at 0} at least 6 I digesting the coal berdeterrnined. For -this p digestion temperature should be employed; on D Second lQ tests ay be run at, lessw de y the other handyif the softening point increases Separated mperatures a h a digestion me- 7 in anormal manner as a-resultof the distillation dium more similar to that use fo -p ar the vgtest; and;the=-incr.ease is proportional tothe perp l Thus I h un a re c ns -i rcentage of distillate,- itmay be concluded that the ing of 50% by weight of a high i ,1 digestion temperature-is adequately highto pro- 11, and 50% of '(,opped cok oven tar -to be a -duce a, stable product.- For-example; a heathighly satisfactory digestion vmedium, and a temstable pitch of the preferred-properties will ordi- V perature interval of abOut IOZ-C- s fl ciently narnarily show an -increase intsoftening-wpoint on" row for my purposes. vilk-typicalcoal-tar 011, cona distillation of at.least 1; C. for. each percent of sideredas characteristic-ofadesirable oil, com-,- distillate to 3007 C. obtained in the distillation ponent of the digestion medium, has the follow: 35, test. a 1 i y ,7 I

1 It isadvantageous to employ'as low adigestion a ing testproperties:

a o temperature as;-per ssible;while-securing the iiiiiittfiii? 'sfT.i. s'?an%;;a ii;e5a

desired results ting statements D246 33): h g v ,l scale-t0 highen'temPeratures: requires more'heat, I Distillate to 210" c auper cent o which Serves no s l ion; Moreover, for. Distillate 6, 0 v0 ther increases in temperature'aresultinan in- .Distillate'to2'70" c' crease temperature i i il y oi the -Distillateto"300 Cs f t; r-"product; and sinceemyapreferredproducts pos- Dismmeto 5 5 SeSS- a v ry low temperature susceptibility, they s Distillate to 3559 c do;;-; 32.3 F tamed-if the digestion ure i 0.. s r I I fififffffflifl-Flfffifiiiinfifi 31 1 followine-resmts'wlth six m ri n bitu- I V ,m'inous coalsselected at random from-the results The topped coke-oven tar, and the' mix'ture iequal. ofan examination of a largewnumber of. 3009.15, parts of oil and tar) 'c m'pr 8 5n demonstrate the; results thatma'y be expected 'rriedium' have the following characteristics? w .in application of the tests previously described.

" Specific gravity Specific gravity Dlstillagiion (a.

D20- v Distillate to 170 0.. Distillate to 235 C Distillate to 270 C. Distillate to 300 C .do

Float test at 70 C. of distillation residue second D -"2Di'ge'stion in, high-boiling -coaltaroilzl, i "Observed dig. temp.

n {or manconsiistency, 1 1 e Method I 4 um i I Softening point oi'distillation residue. (3.. 53 o. 4 selected omimumdi. I

1 1 gestion temperature i i l 4 1 F O. -degrees I Y I The second series of digestions is conducted-1 v oal radios 93 0. p I;

- with standardized conditions and a heating period 7 G 9 g of about one hour at the digestion temperature. i I For these tests sufficlent coal'is empl yed t yield- It may be observed thatthe diiference for these products having a softening point of some definite ,coals between the digestion temperatures for value; forinstance. about 93 C.';:or-' about68 C. umnsistency and the 'optimum'diges- "The 93 C. softening point is advantageous since no tion ternperatures ranges between 35* C. and it has been round that this softening point may 01 Once the optimum digestlon' temp'erature be obtained with relatively minor variations from 1 has been determined for any pam m coal 25% al em loyed "in the tests previously conthat temperature .may be employed without sidered. The products ofthis series of tests are variationfor the preparation of any number of further testedfor their-penetration at 0 C., 25f batches of products from that coal; Digestion the optimum for the the digestion gestion mixture were used.

of coalfor the production of a .will depend upon the properties of-the digestion are made by heating at temperatures substantially higher than the optimum will result in increasing the temperatum-susceptibility ofthe product and usually in a product of lower penetration at C. With certain coalsit may bev advantageous toemploy a digestion temperature somewhat'higherthan purpose oi'zmodifymg the character of product within a desired range.

It will be evident that for the preparation of y the preferred products ofmyinvention the proportion of coal employed should be somewhat below the 25% employed in the teststo determine in the second group of tests listed above where amounts of coal from'l7% to Ti /2% of the di- The exact amount particular product to suit prevailing economic ture of the changes resulting from varying percentages of constituents cannot be strictly generalized but it may be said that with use of a coke-oven tar and a high-boiling oil having the of the present invention together the coal with a digestion medium having the properties pre- In general products viously' described to the digestion temperature.

It isnot necessary that digestion be continued With this procedure normal coal ash remains dispersed to the extent of, say 60% to 100%. the coal was digested in powdered orm, disintegration is more complete and only a small part process. These oils may be separately collected. The charge is gradually heated with continued agitation to the desired digestion temperature. The charge is then allowed to cool, preferably tion.

est digestion temperature of maximum softening with continued agitation, until the temperature" ing properties:

operations the period of the tom perature to around 300 C.-, may be only of hours or less for small quantities of tions of the charge. t H

The apparatus employed for making the prod ucts of my inv'entionmay suitably comprise an ordinary, direct-fired stillyforyexamplea horitions of treatment. t, The following-examples illustrate the inventative sample of this coal was ground to pass a 60 mesh sieveyit had: thefollowing proximate analysis: .v

Per cent 1 Moisture F 1.110 Volatile matter a 29.37 Fixed carbon g 59. Ash 9.68

Perijad of digestion te 0 l 2 3 Denture 7 tion, hrs. a g

C. C. C'. C'. "6'. 0. 245 C. Softening point 53 94% 93 94 93 93 270 oitening point 95 93 96 92 9-3 295? Softening point 91 87 85 82 82 82 1 320 G" Softening point..- 82 76 i 77 75 72 From these tests "it lies between 20 and 100 termined as-foliows: 7 it V prepared consisting of 501 parts having the follow C./l5 .5 C" i C., 6.5%;to 300 to 355*. C. by

A mixture was of the high-boiling coal-tar oil specificlgravity at '38" of distillate to 270 C., 10.5% to 315 C., and 32.3

a'couple v material, I more hours with-larger Example 1. -A bituminous coal obtained from the Lower Freeport Seamin-Pennsylvania was] about plus or minus 2 C. q

-'C. above was then de- 7 ing was observed.

, digestion temperatures of 300C. and 310 her. The results of .thetests were Digestion temperature product of digestidn at 310 sulted in a change recovered had the following properties:

A. s. 'r. M. Standard Method .D246-33; and 50 parts of a topped coke oven tar having theIfol-.: lowing properties; specific gravity at 25 (l/25 C 1.222; 1.6% of distillate to 235C, 7.2% to270 C., and 14.4% to 300? C. by AIS. T. M.'Standard Method 1320-30. mixture 25 parts I -were added and the'mixture was heatedwitnagi- To 75 'parts byiweight of this by weight of pulverized coal tation in a period ofabout two-"andbne-haH hours to a temperature ofabout 290 C. andwas .maintained at this, temperature for one hour.

The product was, cooled to about 200 Cy-with agitation, after .whichit wasallowed to solidifyr The product was then carefully melted, tested for softening point, and distilled toa-ternperature of 300 C. by A. S. "T. MQStand'ard Method D-30. During the distillation excessive foam- Two additionaltests were made with thesame digestion medium and the same coal, employing C.,

respectively. .In orderto obtain products of about the samefsoftening point as obtained by the digestion at 290" C.,- somewhat' higher percentages of coal were digested at the'higher temperatures.

heated to about 310 C. in about eight hours, and

- maintained at that temperature for about one hour, removing volatile oils. one hour,- the product was withdrawn-fromthe still, and had the following properties;.-.

s-softening. pointer C '70 Penetration-at 0C 'l 14 Penetration at C ,30; Penetration at 46. C 80 Specific gravity ze o/25 CA, 1.22": Insoluble in car'bon'disulfide per cent 28 Ash do' "1.24

. softening point ofdistillation fre'si-y Example productpreparedfrom liquid digestion medium meeting the: above ,described requirements .and comprising .50 .parts of Lde hy- 1 drated coke oven tar andi25parts of. neavmoa For these two tests the digestion procedure was the same as for the tests at'290-. C.

and the products were tested in asimil'armanas follows:

' ,C 290 Digestionmedium' parts by weight" 75 .3 74.5 74 al i do i 25; 25,5 26 Softening point ofprodu C 94% 92 I 93 Distillate to 3 9. 5 9. l 8. 9 Softening point of di V I I 1 Theproductsof digestion at 3005c. and 31 0 0.,

properties within the range aboVedeScribed and tar distillate, and 25 parts of coal. byg ses i at 300 .C.with the removal. of=.13-.3%- of -vol;atile oils,yhad the following character tics:

Softening point 80 Penetration at 0,C'. 5 Penetration at 25 C- 14 Penetration at idl" o 3':

" Example 4.-.- To v tar:tair -oi1 having prepared from 72 partsof dehydrated'coke oven tillate weredistilled off during the heating period.

were homogeneous and liquefiedreadily on heat- I ing. The product of digestion at300 C. foamed slightly on distillation .and the distillation. resulted in a change in softening pointof 0.9", C. for each percent of distillate .to 300" C. .The C. ,did not foam excessively on distillation and'the distillation reof softening point of 1.2? C. for each percent of distillate to 300 C. The tests thus established anoptimum digestiontempera- ,ture of. about 3005 c. to 310 c 51 partseof dehydrated coke oven tar and 30 e 7 parts ofheavycoal tar distillate were then mixed to provide a digestion medium having. properties within the range previously described and 19 parts. of pulverized bituminous coal from the Lower Freeport Seam, Pennsylvania were added. The mixture was then heated to' and maintained for one hour at a temperature of about 310 C. During the digestion themixture was agitated and oilva pors were withdrawn; The oil thusremoved and condensed. amounted to "1.7%v by volume of the digestion medium. The. product Softening point C 68 Penetration at-0 C 1'1 Penetration at 25 C; 32 Penetration at 461 C 96 l thejfoll wing propertiesi.

' Penetration at 0" by weight, of dehydrated cokeoven tar and 10 parts of heavy water gastandistillate, 18 parts of pulverized coal wereadde'd, The mixture was heated to 320 C. ,vmame oils amounting to 4.4% by volume of the tarv and dis- The ;product was. then allowed tocool. ,-The

product possessed the following characteristics:

.L 76 Exam l s'eroya mixture eraasj arts by weight of' higheboiling coal-tar oil and 42.5" parts tart havin Specific viscosity, Engler; 8.0;" C -n;

' .jperature of 340 C. for one hour; removing volatile. oils amounting to 12.5% 'by volume of the digestion medium. The product "had the following properties:

Example 2.'-l8,6'll pounds of bituminous coal from the Lower Freeport Seam, Pennsylvania were pulverized to pass a No. 8 sieve. The coal was charged in a commercial still equipped for agitation and containing 38,770 pounds of dehydrated coke oven tar and 28,158 pounds of high-boiling coal tar oil. The mixture of cokeoven tar and coal tar oil had properties within the range previously disclosed. The charge was ing points are determined by The rmxture wasjdigested at a tem- Softening point l c 'zo Penetration at 0 C; -c 2 6 Penetration at 25 C 69 Penetration at 46.1 C 193 The tests outlined throughout this specification are performed in accordance with standard apparatus and procedure prescribed by the American Society for Testing Materials. Softenthe ring and ball method. Penetration is given in units of one- After settling for volatile bituminous coal I more than 25% distillable below 300" mixture of digestion perature between 20 tion temperature corresponding to a product of said bituminous prodand about 90 7 g 4, and a penetration at"25 'C. not more than flve times thepenetration at O. f e 1 2A heat-stable bituminous product suitable 'foruse as a steep-roofing pitch, particularly tainable by heating and containing than 5% than a distillable below 300 C.. with between 'being based 'upon'the total tion at 25 tration atz0 C. v

} .C./15.5 C. a specific 1.20, an Engler specific viscosity not less, than 0., a float test of residue from distillae tenth oi. a millimeter with. weights and periods as follows:

At 0' C; 200 grams, 60 seconds .At25 C 100 grams, 5 seconds At 461 C- .50 grams, 5seconds This application is acontinuation in part of my copending application Serial No. 749,618, fl1ed October 23, 1934. I

I claim: e 1. A heat-stable bituminous product, particularly adapted for application by remelting, obtainable by heating a digestion medium.

comprising tar oil and pitch constituents and having a floatftest of residue from distillation to 300 0. not above 130 seconds at 70 C; andcontaining distillable oils including not distillable below 235 Cpand not more than 5%:

k 0., with be tween 7% and 25% of a coal oi the groupconsisting or bituminous 0081981101 sub-bituminous coal, the perecentage being based upon the'total medium and coal. toa .temabove the digesand 100 maximumsoitening point, uct having a softening point'between about C., a penetration at 0 C. at least 2,304,773- I j than 5% distillable, elow 235 1 5% and 2.5%,

medium and 46.1 C. not more than 120. p I p l 4. Themethod of preparing a bituminous'jprod, not, which comprises heating'la digestion niedi-,

and pitch, constituents 1 p C. and notmo than 25% distillable be1OW=300 the, digestion t p rature eerie.

spending to a. product of maximum softening;- pointysaid bituminousproduct having a soften,- ing point between about C. and about 80C.,

at least 6; la penetrationflat 1 a.

.a penetration'at' a vpenetration at 0 25 C. between 20 and 40,.and

um, comprising tar oil and having afloat test of residueirom dis'tilla tion to 300 C. not above 130' seconds at C.

adapted for application by r'emelting, and obprising tar oil and pitch constituents and havingat 38 C./f15.'5 1.1 and 1.22,,an Engler specific viscosity not less than 2.0 at C., a float test of residue from distillation to 300 C. not above 130 seconds at 70 C. distillable oils including not more distillable be1ow235j C. and not more o1 bituminous coal, the percentage mixture of digestion medium and coal, to a temperature between 20 and 100 above the digestion temperaturetcor- 7% and 25% responding to a product of maximum softening point, said bituminous product having a softening point between about 50 and about 0., a

penetration at 0-C. at least 4, and a :penetra- C. not more 3. A heat-stablebituminous product. suitable as a coating-and bonding material for :coal-tarpitch-impregnated roofing fabric on steep roofs,

and particularly adapted for application by remelting, able by tar, oil

and pitch constituents and having at 38 gravity between 1.10 and tion to 300 C. and

C. not above 80 seconds at70 containing distillable oilsincluding not more C. a specific gravity between a digestion medium, comproduct suitable as than flvetimesthe penesaid bituminous product being obtain- 1 heating a digestion medium; comprising 1" Z product of maximum softening point.

, constituents and having at 38 1 and contaming-distillable oilsincluding .not more than 5% distillable be1ow235 C.\and..notmore' than.25% 'distillablelbeldwl 30o c. with between" 7% and 25% percentage being based upon the tot'ai mixture jor digestion medium and coal, tota temperature between 20 and above the',digestiontemperature correspondingto a product of maxi-Y mum softening point. t

5. The method of which comprises heating 1 a digestion medium comprisingtar oil and ing at.38 c./15.5

tion to 300 C. not

than 25% distillable below 300"" of bituminous c'oahthe percentage being based upon the totalmixture-or digestion medium and coal, to a temperature between-20 above the digestion temperature "corre l g spondin'gto a product ot-maximurn softening;

and 100 point.

' 6.' The method cific gravity between 1.10 and 1.20.511:

and not more than 25% C1" the distillable below 300 25% bituminous coal,

coal, to a temperature between 20-and 100. above the digestion temperature corresponding BENJAMIN ALBERT amna'ron.

c.. with betweenf of bituminous coal, the percentage beingbased upon the total mixture ofedigestion coal, to a temperature between 20 of acoal of the group consisting. v bituminous coal and sub-bituminous coal, the

Y preparing: a bituminous l product suitable for use asja steeperoofing'pitch pitch constituentsiand hav- C a speciflcgravity between L1 V and 1.22, an Engler specific viscosity not less than 2.0 at 80 0., a float test of residue from distillaabove-130,secohds"at.70. Ciand I containing distillable oilsincluding' not more than 5% distillable belowi235". O land notfrnore 0., with between of preparing a; bituminous" I a coating and bondingniae. 1 terial aforcoal-tarpitch. impregnated roofing C. /15.5 C. aspev- Engler speciflc' viscosity not'less than. 2.10 at 80C., a, float test of residueirom distiIlation5t6 300 C.- I not above 80 secondsat70 I 'dis tillab1e 0115' including notmore than5'% dis-' tillable' below 235 C.

C. and containing withibetweenfl5 %"and v percentage'bein'g'based upon the total mixtureo'i' digestion medium and e 

